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Full text of "Alaskan glacier studies of the National Geographic Society in the Yakutat Bay, Prince William Sound and lower Copper River regions"

446                                ALASKAN GLACIER STUDIES
SMALL ICE TONGUBS NORTH OP ALLEN GLACIER
La Gorce Glacier. In the valley immediately east of the terminus of Allen Glacier there is a small ice stream called La Gorce Glacier.1 It is a valley glacier a little smaller than Grinnell Glacier and terminates about 2 miles from Copper River. This ice stream flows with a rather steep grade from a large cirque. Its terminus is mantled with d6bris. There is a strong lateral moraine on the valley side east of the glacier margin, which seems ! to be of recent formation. A broad valley train of outwash gravels leads from the glacier to the Copper River.
The mouth of the valley of La Gorce glacier is exceptionally steep-sided because of glacial erosion. It seems clear that the La Gorce valley formerly mouthed at least a mile farther north and that the Copper River now sweeps through the mouth of La Gorce valley (PI. CLXXIV) in the portion of its course south of the 600 foot rock hill near Allen Glacier. This hill was formerly the termination of a spur on the northern side of La Gorce valley. Allen Glacier seems to have forced the Copper River into a marginal channel which crossed this spur and entered La Gorce valley, the river then sawing off the end of the spur and converting it into a detached rock. It is concluded that this diversion was related to an earlier expansion of Allen Glacier than the present one because the channel east of the rock hill is not a narrow, steep-sided gorge, but has been opened out to a width of a quarter mile with flaring walls. This is ascribed to erosion by the former trunk glacier of the Copper River valley. The expansion of Allen Glacier is thought to antedate this, and the reoccupation by Copper River of this modified marginal channel may be due to alluviation by the glacial streams on the northern side of Allen Glacier.
Wernicke Glacier.1 Wernicke River enters the Copper River valley northeast of Allen Glacier, flowing in scores of channels over a gravelly valley train a mile wide. We have not visited the glacier at the head of this valley but from the many streams it is judged to be of considerable size.
Shields Glacier, Shields Glacier! is a small valley glacier on the western side of Copper River valley about 6 miles north of Allen Glacier. It terminates near the lip of its hanging valley (PI. CLXXIX).
Smaller Ice Masses. A Ranging valley south of Shields Glacier still retains a small glacier. There are several on the valley wall north of the La Gorce Glacier, two of which come so nearly in line that they give the erroneous impression of a recemented glacier.
North of Wernicke River there is a neve-sheathed slope of the type seen in Harriman Fiord. This ice expands on a moderately steep slope and terminated in 1910 just above a barren zone, where there was formerly a steep ice cascade.
HENEY GLACIEB
Location. Heney Glacier is on the western side of Copper River 10 miles north of Allen Glacier. The portion of the Copper River canyon near Heney Glacier is 2 to 4 miles wide with the mountain walls on each side rising precipitously over 5000 feet. Instead of being blocked by glaciers that project clear across the valley from either side, as Allen
1 Named in 1910 for John 0. LaGorce, assistant editor of the National Geographic Magazine. * Named in 1910 for L. Wernicke and Archie Shields of the Copper River and Northern Railway.